1. Field of the Invention
The present invention relates generally to systems for operating coverings for architectural openings, such as doors, windows, archways and the like, wherein the covering is a top down/bottom up covering including a head rail, a bottom rail and a middle rail with a shade material extending between the middle and bottom rails. A single operating cord is utilized to raise and lower the middle and bottom rails independently of each other, but in one continuous motion so that the shade material can be deployed to any desired degree from the head rail down or from a bottom sill up.
2. A Description of the Relevant Art
Coverings for architectural openings have assumed many variations over a long period of time with early coverings simply being fabric draped across the architectural opening which could be a window, door, archway or the like. More recently, however, retractable coverings have been popular and have assumed numerous variations.
A popular retractable covering for architectural openings is a Venetian blind wherein a plurality of horizontally disposed slats are supported on cord ladders so that the blind can be extended across the covering or retracted adjacent one side. Further, when the blind is extended, the slats can be pivoted about their longitudinal axes between open and closed positions to permit or block vision and light through the blind.
Similarly, retractable vertical blinds have also been popular and are very similar to Venetian blinds, except the slats are vertically suspended rather than being supported horizontally. The slats can be gathered adjacent one side of the opening in a retracted position or extended across the opening in an evenly distributed array. Further, when the blind is extended, the slats can be rotated about their longitudinal vertical axes for pivotal movement between open and closed positions.
More recently, cellular blinds have become popular, which have assumed numerous forms including transversely collapsible cells that are interconnected along their length. The cells are typically disposed horizontally so in aggregate they form a panel of material that can be extended across the opening or gathered adjacent to one edge of the opening by transversely collapsing the cells. Other forms of cellular coverings have included a pair of transparent sheets of sheer fabric or the like which are interconnected at evenly spaced intervals by parallel vanes so as to form cells therebetween. By shifting the sheer fabrics in opposite vertical directions, the vanes can be opened or closed and the entire panel of material can be rolled or otherwise gathered adjacent one edge of the opening or extended across the opening.
More recently, retractable shades or blinds, where appropriate, have been designed so they include a head rail in which the control system for the blind is housed, a bottom rail, a middle rail and a shade material extending between the bottom rail and middle rail. The control system for the blind enables the bottom rail to be raised or lowered independently of the middle rail so that the shade material can be extended to any desired degree between the middle and bottom rails. The control systems for moving the middle and bottom rails so as to desirably position the shade material within the architectural opening have varied and typically include independent control systems for operating the middle rail and the bottom rail. These control systems might typically include a flexible control element at each end of the head rail.
It is to provide improvements in control systems for operating top down/bottom up coverings for architectural openings that the present invention has been developed.